In order to coat a coating diffusion agent or photo resist solution, etc. on various kinds of substrates (circular or rectangular type), it is general that a rotary coating equipment in which rotary centrifugal force of a spindle is utilized has been used.
In this rotary coating equipment, a substrate is adsorbed and retained to the upper surface of said spindle. Said coating solution or agent is dropped on the center of the surface of said substrate with said spindle stopped. After that said spindle is started and said coating solution or agent is spread to the whole surface of said substrate by virtue of centrifugal force of said spindle. At the same time, unnecessary solution is splashed out outside said substrate, thereby causing a film of said coating solution or agent (diffusion agent or photo resist agent) to be made uniform in thickness on the surface of said substrate. However, if such coating film is formed by a rotary coating equipment of the above structure, the peripheral portions of the whole surface of a coating solution or agent on said substrate may be adversely influenced by wind or aerial stream which is generated by rotation of said spindle, and said peripheral portions may be first dried, thereby causing the viscosity to become higher and higher. As a result, finally said coating solution or agent at said peripheral portions is hardened. Therefore, in this conventional rotary coating equipment, it is very difficult to coat said coating solution or agent uniformly or to form a uniform film thickness of said coating solution or agent on said substrate. The larger a substrate becomes, the larger this tendency (or influence) may become. In addition, if a substrate is rectangular, this tendency (or influence) may become a great problem.
As a method for unifying the coated film thickness, another coating equipment shown in FIG. 5 has been proposed, comprising that a substrate is placed on the upper surface of a spindle "1'" and a vessel "3'" which rotates in synchronization with said spindle is so composed that it can wrap said substrate "1'" placed on said spindle. However, coating solution or agent which becomes unnecessary in formation of coating film on said substrates is splashed out to the bottom and the side walls of said vessel "3'" outside said substrate. Therefore, it is impossible to continuously treat and coat as spinning, and the productivity is very poor.